Re: Xen on Raspberry Pi 4

[Paul Leiber <paul@xxxxxxxxxxxxxxxx>]

Am 11.08.2023 um 20:51 schrieb Julien Grall:
> Hi Paul,
>
> On 04/08/2023 06:44, Paul Leiber wrote:
> > Am 02.08.2023 um 23:03 schrieb Julien Grall:
> > > On 02/08/2023 21:42, Paul Leiber wrote:
> > > > Hi list,
> > > Hi Paul,
> > >
> > > > What I did was to install a standard Debian distribution booted via 
> > > > EFI/GRUB2 (following 
> > > > https://forums.raspberrypi.com/viewtopic.php?t=282839) and then 
> > > > install the xen-System-arm64 package via apt. I have output on a 
> > > > console via UART (at least when booting Debian without Xen, see 
> > > > hypothesis 3 below).
> > > > Booting Debian without Xen is working fine. (Although I only see the 
> > > > Grub selection menu via UART when no HDMI is plugged in while booting.)
> > > > Selecting Xen in Grub leads to the following output on the console 
> > > > right after Grub hands over:
> > > > Loading Xen 4.17-arm64.efi ...
> > > > Loading Linux 6.1.0-10-arm64 ...
> > > > Loading initial ramdisk ...
> > > > Using modules provided by bootloader in FDT
> > > > Xen 4.17.2-pre (c/s ) EFI loader
> > > >
> > > > And then the output stops.
> > > I have been using Debian + Xen + Grub + UEFI on Rpi4. UEFI firmwares 
> > > are mostly shipped with ACPI only (IOW no Device-Tree support) This 
> > > is not yet a fully supported configuration on Arm64 and therefore not 
> > > enabled by default.
> > > Can you check the kernel log when booting Debian without Xen for 
> > > anything referring to ACPI? If so, you will need to Xen build 
> > > yourself to enable ACPI (this is protected by EXPERT). Alternatively 
> > > you could use U-boot where Device-Tree boot will be available.
> > Indeed, the device is using ACPI. There is an option in the UEFI 
> > settings to switch to Device-Tree, but that didn't have any effect I 
> > could see, other than plain Debian didn't boot anymore either.
> > I compiled Xen with the ACPI option for Arm, and got it running. Thank 
> > you very much for your hint, Julien!
> > For reference:
> >
> > To enable the ACPI option, I went to the "xen" subdirectory in the Xen 
> > source main directory after "git clone" and did a "make menuconfig".
> > Out of convience, I initially intended to only rebuild the Debian Xen 
> > hypervisor package with the ACPI switch on, but that didn't work 
> > somehow. I couldn't find out why.
> Is Debian using 4.17.2? Did you see any output from Xen/Linux.
xl info on a standard Debian installation gives me version 4.17.2-pre. 
If I remember correctly, the output when booting both my self-compiled 
Debian xen package or the self-compiled 17.1 version is identical to the 
one above, it stops with:
Using modules provided by bootloader in FDT
Xen 4.17.2-pre (c/s ) EFI loader

> > I then created a "Frankenxen" with a newly built hypervisor and 
> > standard debian tools, which booted (yay!), but of course the xen 
> > tools didn't work. Using the repo to check out a Xen 17.1 version and 
> > build the hypervisor (so I could still rely on Debian updates for all 
> > the other Xen packages) also didn't work, Xen didn't boot. I then 
> > decided to build a complete Xen version from scratch from the master 
> > repo, which worked well. So perhaps this approach with enabling ACPI 
> > only works on Xen versions > 17.1?
> I don't remember any change related to ACPI on Arm that are in master 
> but not 4.17. I will try to have a look in the next couple of weeks and 
> find which patches may be missing.
Let me know if I can help.

Paul